Welcome to the forums..The component end of PSU connectors have to conform to industry-standard ATX PSU specifications..The PSU end of modular connectors is a different story because there are no industry-standard specifications and can vary by PSU manufacturer and even between different units of the same manufacturer which can cause big problems for those who use cables that were not originally included with the PSU or when not paying attention during cable sleeving..Many people have burned up components (particularly SATA drives) by replacing their PSU with one from a different manufacturer and just leaving the modular wiring in place connected to their components and then connecting another PSU to the existing wiring simply because it's easier that way..Then, power on = POOF!..You didn't say, but something tells me you're having an issue like this, yes?..If not, then please explain..In the meantime, I'll keep rambling on, lol.
 
If it helps, here is a diagram from another forum member in post #4 for the PSU end of a 750G..Here in post #5 is EVGATech_MattV confirming the 24-pin connector pinout is the same for 650G, 750G and 1500W power supplies..I won't presume the the other connector pinouts are the same as the 650G though..Best bet would be to get a digital multimeter and map out what goes to what, and where..You can find ATX pinout charts everywhere if you search, look here at the references and external links at the bottom of the webpage..You can turn on your PSU manually (search: "hotwire PSU") to check voltages without it being connected to your PC by jumping pins 16 (PS_ON) and 17 (COM) of the 24-pin connector..Some units won't turn on unless a load of some sort is detected, so you may need to connect a fan or a drive.
 
Hope that helps.